The function of your drainage system is incredibly important – both to the comfort of your family and to the safety of your property. Even when we’re not aware, we rely on it heavily to help move waste and sub-surface water from a specific area to another. The drainage systems built into our homes are designed to move sewage, rainwater and other liquid deposits to maintain health conditions in and around the building. We are unlikely to pay much attention to our drainage systems until something goes wrong. And, in these times, it pays to understand as much as possible about the options available to you.

The Roles of Residential Drainage Systems

In your home, there will be two different types of drainage systems – foul drainage and surface water drainage. They sit independently from each other but play an important role alongside each other. Let’s take a look at each in more detail here.

Foul Drainage

Your foul water drainage system is designed to take wastewater away from the bathroom, kitchen and utility room. It drains the water used in toilets, baths, sinks, washing machines, dishwashers, showers and any other appliance that connects to your mains water system. Once this water becomes soiled, the following process takes place:

  • The water drains through your pipework and joins the communal sewer.
  • Here, it mixed with the soiled wastewater from your neighbours and local community too.
  • The wastewater is transported to your local sewage treatment plant.
  • Here, it is screened to remove larger items that should not have made it into the pipework. These include baby wipes, condoms, nappies and sanitary items.
  • The water then passes through stage one of treatment where all solids are removed.
  • After this process, good bacteria is used to dissolve away smaller, less visible fragments.
  • Finally, bacteria are separated from the water which leaves it clear.
  • Once the water has been through these three stages, it is then drained back into local rivers and seas.
  • This water eventually evaporates and falls back down to the ground as rainfall.
  • The water that ends up in aquifers and specific rivers is re-collected and sent back to our homes to begin the whole process again.

Legal Regulations Surrounding Foul Drainage Systems

Foul drainage systems are covered in Part H of the UK Building Regulations. This is largely because of the polluting potential of this water if it is not properly transported to the sewage plant and treated. The regulations state that, as a priority, foul waste should be disposed of via the public sewer. However, they recognised that this isn’t always possible for certain properties – whether this is because of the remote location or type of ground. In these cases, the waste should be removed via one of the following options (in order of preference):

  • A private sewer connecting to the public sewer.
  • A septic tank/waste treatment plant found on the property premises.
  • A cesspit.

Within the regulations, they also guide alterations and changes to a property that could impact foul drainage. These include:

  • Pipework needs to be sized for the predicted flow of water to reduce the risk of blockages and allow air movement.
  • Sanitary pipework (foul drainage pipework found overground) should be designed with access hatches.
  • Sanitary pipework should be capable of being dismantled to help deal with blockages.
  • Rodding eyes and access chambers should be used to enable all parts of underground drainage to be cleared.
  • Sanitary pipework needs to be appropriately ventilated by extending the pipework outside of a building (a minimum of 3m to the side of, or extended 0.9m above, the opening of the building.

Surface Water Drainage

The alternative form of drainage in a property is designed to move the rainwater away from the roof of your property and paved areas. The vast majority of rainfall will drain into public sewers, becoming the responsibility of the major sewage companies to treat and process. It also refers to the drainage of water from activities, including washing a car. A well maintained and designed drainage system will:

  • Prevent water accumulation which can lead to flooring.
  • Reduces the risk of soil erosion and helps to maintain balanced moisture for crops.
  • Prevents water from pooling on flat roofs which, over time, can stress the roof materials and cause damage.
  • Supports the reduction of water pollution and scarcity.

Your surface water drainage is made up of elements such as your guttering system. These lightweight but durable pipes work their way from your roof to the ground, providing a clear route for water to run through.

In the UK, more surface water will enter the public sewer. As a result, every homeowner will pay a charge to support the processing and treatment of this water. However, in some situations, water that runs off of the roof and from driveways enters a soakaway – a system where water is piped through to an underwater pit. Households with soakaways can claim a rebate from their local water provider.

Legal Regulations Surrounding Surface Drainage

Surface drainage systems are also subject to Part H of the Building Regulations here in the UK. The requirements include:

  • If you increase the size of your roof, you may need to increase the size of your gutters and rainwater pipes to assist.
  • If any rainwater pipes discharge onto the ground, you need to actively ensure it will not damage the foundations or flow into a nearby property.
  • The increase in surface water expected should be managed on-site, where possible, to reduce the risk of flooding. You may need to consider a soakaway or an infiltration system.
  • Consider having new patios or driveways sloped towards permeable ground or have it manufactured from pervious materials like clay or concrete.
  • Any surface water from hardstanding cannot run onto highways.
  • If you cannot use pervious materials, you should try to keep surface water on-site by using a soakaway or infiltration system.

Both foul drainage systems and surface drainage systems are vital to the everyday use and safety of your property. With the support of a specialist team, such as our expert engineers here at West Country Drainage, you can decide on the best solutions to meet your requirements and budget. If you are concerned about leaks, are looking to replace your existing drainage system or need additional support, get in contact with the team here today.